Fig. 4. Effects of CTA1-DD adjuvant on germinal center responses in neonatal mice.

Adult and neonatal (5–7-days-old) mice were immunized with 5 µg NP-OVA alone (gray) or admixed with 5 µg CTA1-DD (black) s.c. and boosted at d30 post prime with 5 µg NP-OVA s.c. a Representative FACS plots of GC B cells (CD19⁺ IgD^lo CD38^lo Fas⁺ GL-7⁺) in the iLN following immunization with the indicated frequency of Fas⁺ GL7⁺ cells in the gated population of IgD^lo CD38^lo B cells. b The frequency and absolute number of GC B cells of total CD19⁺ B cells in the iLN of neonatal and adult mice on day 10 post prime (upper panel) or day 5 post boost (d.35, lower panel). c Representative FACS plots of TFH cells (CD4⁺ Foxp3⁻ CD44⁺ CXCR5⁺ PD1⁺) in the iLN following immunization with the indicated frequencies of CXCR5⁺ PD1 + cells in the gated population of CD62L^- CD44⁺ CD4⁺ T cells. d The frequency and absolute number of TFH cells of total CD4⁺ T cells in the iLN of neonatal and adult mice on day 10 post prime (upper panel) or day 5 post boost (d.35, lower panel). e Linear regression analysis of the correlation between the frequency of TFH and GC B cells in CTA1-DD immunized neonatal mice as compared to that found in adult mice after s.c priming (d.10) or booster (d.35) immunizations. f An increase in Bcl-6 expression in TFH cells in response to CTA1-DD adjuvant is given as the ratio of MFI levels exhibited by TFH over non-TFH CD4 T cells in neonatal mice following a priming immunization (day 10) or after a booster dose (day 35). For b, d, and f statistical analysis was performed using two-way ANOVA followed by Dunnet correction for multiple comparison; *p < 0.05, **p < 0.01, ****p < 0.0001.